diff --git a/phase1.dyalog b/phase1.dyalog
index a2e5aa3..07c9234 100644
--- a/phase1.dyalog
+++ b/phase1.dyalog
@@ -9,3 +9,5 @@
  {⍵[⍋⍺≠⍵]}
  ⍝ 7: See You in a Bit
  {f←⍸∘⌽(2∘⊥⍣¯1)⋄∧/(f⍺)∊f⍵}
+ ⍝ 8: Zigzag Numbers
+ (∧/2 ¯2∊⍨2-/∘×2-/(10∘⊥⍣¯1))